reactos/lib/sdk/crt/string/strtoull.c

   1 #include <precomp.h>
   2
   3 unsigned long long
   4 strtoull(const char *nptr, char **endptr, int base)
   5 {
   6   const char *s = nptr;
   7   unsigned long long acc;
   8   int c;
   9   unsigned long long cutoff;
  10   int neg = 0, any, cutlim;
  11
  12   /*
  13    * See strtol for comments as to the logic used.
  14    */
  15   do {
  16     c = *s++;
  17   } while (isspace(c));
  18   if (c == '-')
  19   {
  20     neg = 1;
  21     c = *s++;
  22   }
  23   else if (c == '+')
  24     c = *s++;
  25   if ((base == 0 || base == 16) &&
  26       c == '0' && (*s == 'x' || *s == 'X'))
  27   {
  28     c = s[1];
  29     s += 2;
  30     base = 16;
  31   }
  32   if (base == 0)
  33     base = c == '0' ? 8 : 10;
  34   cutoff = (unsigned long long)ULLONG_MAX / (unsigned long long)base;
  35   cutlim = (unsigned long long)ULLONG_MAX % (unsigned long long)base;
  36   for (acc = 0, any = 0;; c = *s++)
  37   {
  38     if (isdigit(c))
  39       c -= '0';
  40     else if (isalpha(c))
  41       c -= isupper(c) ? 'A' - 10 : 'a' - 10;
  42     else
  43       break;
  44     if (c >= base)
  45       break;
  46     if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
  47       any = -1;
  48     else {
  49       any = 1;
  50       acc *= base;
  51       acc += c;
  52     }
  53   }
  54   if (any < 0)
  55   {
  56     acc = ULLONG_MAX;
  57 #ifndef _LIBCNT_
  58     _set_errno(ERANGE);
  59 #endif
  60   }
  61   else if (neg)
  62     acc = 0-acc;
  63   if (endptr != 0)
  64     *endptr = any ? (char *)((size_t)(s - 1)) : (char *)((size_t)nptr);
  65   return acc;
  66 }